sounds like a diesel, that can't be good

neal c. · 07-14-2003, 08:25 PM

If its not one thing, then it's another.
Still have not fixed the oil leak but when I started the thing today to drive it up on the ramp it sounded like a diesel when I stepped on the gas. What could be the problem??? I did check the oil level before starting up.
Sounds ok when at idle, noise is there at every revolution, I think, only when I give it gas. I think, it is running on all four barrels.
Help, please!

Neal

Kevin Powers · 07-15-2003, 07:21 AM

like a wham, wham, wham. or a clunk, clunk, clunk? does the noise speed up with rpm? does the sound go away as the engine heats up? if you put the sole of you shoe over the exhaust pipe (as in pugged) does the engine load up and stumble?

kevin

airsix · 07-15-2003, 10:11 AM

The "sounds like a diesel" noise is probably detonation. This can be caused by the mixture being too lean, the ignition having too much advance, the engine being too hot, or a combination of any or all of those factors. It is very hard on the pistons and bearings.
-Ben M.

neal c. · 07-15-2003, 06:59 PM

Kevin & Ben, thanks for the reply.
Engine sounds excactly like a diesel truck starting on a cold morning. Sounds the same hot or cold. Plugging the exhaust slows the engine down but no stumbling or missing. I rotated the distributor small amounts both to retard and advance, no difference in sound. I checked for vacuum leaks and replaced some of the hoses, no difference.
Pulled the plugs, look normal to me.
What else could I check????

Neal

chrisreale · 07-15-2003, 09:22 PM

Exhaust leak?

Kevin Powers · 07-16-2003, 03:44 AM

the diesel start up up sound reminds me of my ages ago kharman ghia. if you listen in the engine compartment is it really noticeable? like it is centered in the engine? anyoneone else think it could be a bad main bearing? a wham, wham that quieted down when it warmed up. then the rod came through the case! at speed on the freeway!! VERY exciting.

kevin

SGB · SGB's Garage

How long since yer last valve adjustment? Do you have carbs or FI? I've got carbs and hydraulic webcam. I used to get what I called "loose valve clatter" until the push rods pumped up. Finally replaced my original oil pump with a high volume unit, which helped me achieve a better valve adjust since the the PR stayed pumped up. On a solid PR engine, I think you could get the same effect if the valves are too loose (which I used to do on purpose since I had fried a VW motor that had "creeping valve syndrome" by continually reducing the PR/rocker clearance which kept changing- I think because of a bad rocker assembly). So, what I found out was that when the valve timing is correct, the motor was a lot quieter. Is it possible that a valve is not properly adjusted or the rocker assembly isn't torqued down? Fter I was sure valve settings were right, I messed with the air bypass part of my webers to increase richness but reduce volume of air/gas mixture at idle. Made it a whole lot smoother. Perhaps there are similar adjustments on the FI? Lastly, how are the plug wires? A poorly firing cylinder creates valve noise too. I got magnacores from Pelican too and that made a big difference.

unclerichy · 07-16-2003, 07:59 AM

If it's really loud (and a 2ltr) it could be a dropped valve seat.

neal c. · 07-16-2003, 07:17 PM

Thanks for the suggestions.
I drove around the block today to check if the noise changes under load. Then I noticed the oil light on, the light stayed on....
Turned off the ignition, pushed the beast home, disconnected the battery and started to organise tools for the coming rebuild..
I'll keep you posted about the problem.

Thanks,
Neal